This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A291504 #28 Aug 26 2017 13:17:21 %S A291504 1,1,0,1,3,8,48,206,1838,13336,133764,1081556,11046816,108196128, %T A291504 1555323224,16279258144,289771660328,3495882548784,66923393467216, %U A291504 942785369844048,15625264115770992,315553823251866304,5974132307015712032,104979988889030774848 %N A291504 Number of permutations s_1,s_2,...,s_n of 1,2,...,n such that for all j=1,2,...,n, Sum_{i=1..j} s_i is not a prime. %e A291504 1 is not a prime, %e A291504 1 + 3 is not a prime, %e A291504 1 + 3 + 2 is not a prime, %e A291504 1 + 3 + 2 + 4 is not a prime. %e A291504 So [1, 3, 2, 4] satisfies all the conditions. %e A291504 --------------------------------------------- %e A291504 a(1) = 1: [[1]]; %e A291504 a(3) = 1: [[1, 3, 2]]; %e A291504 a(4) = 3: [[1, 3, 2, 4], [1, 3, 4, 2], [4, 2, 3, 1]]; %e A291504 a(5) = 8: [[1, 3, 2, 4, 5], [1, 3, 4, 2, 5], [1, 5, 2, 4, 3], [1, 5, 4, 2, 3], [4, 2, 3, 1, 5], [4, 2, 3, 5, 1], [4, 5, 1, 2, 3], [4, 5, 3, 2, 1]]. %t A291504 Table[Count[Permutations@ Range@ n, _?(AllTrue[Accumulate@ #, ! PrimeQ@ # &] &)], {n, 0, 10}] (* _Michael De Vlieger_, Aug 26 2017 *) %Y A291504 Cf. A067957, A291355. %K A291504 nonn %O A291504 0,5 %A A291504 _Seiichi Manyama_, Aug 25 2017 %E A291504 a(0), a(12)-a(23) from _Alois P. Heinz_, Aug 25 2017